I have some experience in this area. If ten people rely on firewood for heat, and if they live there in the winter, and if the island is heavily forested, the trees will last maybe five years before any further cutting will start eating into property value and privacy.
I'm actually really into learning about forest management. I've been reading a lot about it, and it's fascinating stuff. Based on our usage, it seems that we should be fine, especially since few people will be coming in winter. My bigger concern right now is bringing back birch trees! We have some dead ones, but very few live ones. The whole island is balsamic fir right now, so it smells like Christmas trees.
At 5 acres, are you concerned at all about deforesting it too much over time?